Compositions for drilling fluids useful to provide flat temperature rheology to such fluids over a wide temperature range and drilling fluids containing such compositions

ABSTRACT

The invention is of oil-based drilling fluids including invert emulsion fluids that are able to maintain a relatively consistent rheological profile over a wide temperature range. The invention also includes new additives that enable the preparation of drilling fluids with viscosities that are less affected by temperature over a temperature range from less than about 40° F. to more than about 250° F. compared to conventional fluids. These additives are based on reaction products of polyamines and carboxylic acids with two or more carboxylic moieties combined with alkoxylated amines and fatty acid amides. In addition, this invention permits the use of reduced amounts of organoclay rheological additives in drilling fluids.

FIELD OF THE INVENTION

[0001] This invention relates to compositions suitable for use asadditives for drilling fluids, and to drilling fluids comprising saidcompositions having improved rheological properties. The invention alsorelates to additives that provide rheological properties to drillingfluids relatively independent of the varying temperatures encountered inoil well drilling operations at various depths, particularly in deepwater drilling.

BACKGROUND OF THE INVENTION

[0002] Drilling fluids have been used since the very beginning of oilwell drilling operations in the United States and drilling fluids andtheir chemistry have been and remain an important area for scientificand chemical investigations. The use and desired properties of drillingfluids are comprehensively reviewed in recent U.S. Pat. Nos. 6,339,048and 6,462,096, issued to the assignee of this application, the entiredisclosures of which are incorporated herein by reference.

[0003] A drilling fluid is a thixotropic system and exhibits lowviscosity when sheared during cutting of the hole into the ground,during agitation and circulation but, when such shearing action ishalted, must quickly thicken to among other things hold the “cuttings”from the drill hole in place without sinking. The fluid must thereforebecome thick rapidly, reaching sufficient gel strength before suchsuspended materials fall any significant distance. Importantly, thisbehavior must be totally reversible at all temperatures encountered inthe borehole. In addition, even when the drilling fluid is free flowing,it must retain a sufficiently high viscosity to carry all cuttings andother particulate matter from the bottom of the hole back up to thesurface.

[0004] Since the end of the second World War, hydrocarbon drilling forexploratory and production wells has increasingly been done fromplatforms located in water settings, often called off-shore drilling.Such fresh and salt water drilling employs floating barges and rigsoften fixed in some fashion to the submerged surface of the earth.

[0005] Economic and technical advances have recently pushed thesedrilling operations into deeper waters. Although advances in equipmentand engineering have yielded technology capable of drilling in waterdepths up to 10,000 feet or more, advances required in drilling fluidtechnology have lagged.

[0006] A major problem with oil-based drilling fluids in deepwaterdrilling is rheological additive temperature sensitivity over thetemperature range encountered. During circulation, the drilling fluidtypically reaches bottom hole temperatures of about 60 to 80° C.followed by cooling to lower than 5° C. in the riser during its travelupward (due to the inherent low temperature of sea water far below theocean surface). For successful deepwater drilling, the mud needs tosimultaneously suspend the solids and remain pumpable with properviscosity over these wide temperature ranges.

[0007] Drilling fluids thickened with conventional organophilic clayrheological additives particularly suffer considerable viscosity buildas the drilling fluid is cooled from a temperature of 60 to 5° C., forexample. As a result of this viscosity increase, the drilling fluid,when it reaches low temperatures, is more difficult to pump, theequivalent circulating density (ECD) is increased and losses to theformation (lost circulation) frequently increase.

[0008] The requirements for drilling fluids with enhanced temperatureproperties have also become more complex over the past two decades as aresult of changes in directional drilling technology, in which a well isdrilled at an angle other than vertical. Such wells are widely known asdeviated wells.

[0009] Methods for drilling deviating wells have changed greatly overrecent years with the production of more powerful and reliable downholemotors, and the invention of more accurate methods utilizing wirelinetechniques as well as the highly computerized downhole, sensing andmicro reduction equipment, including improvements in sounding apparatusand microwave transmission. These techniques permit the instantaneousacquisition of data relating to down-hole conditions without the need toremove the drill string and in fact mean that holes can, and are,drilled at ever increasing lengths.

[0010] The advantages of directional drilling include (1) directionaldrilling allows tapping of fields which cannot effectively be reached byvertical drilling; (2) such drilling permits the use of more economicalland-based equipment to explore the immediate off-shore environment; and(3) such drilling make possible the drilling of multiple wells up toseveral miles from one another, sharing the cost of a single site. Inaddition, in certain geological formations, increased production can beachieved by deviating the well off-vertical so as to facilitateperforation and development of a narrow producing zone, or redevelopmentof a depleted formation.

[0011] Use of a downhole motor allows the hole to be deviated by theintroduction of a fixed offset or bend just above the drill bit. Thisoffset or bend can be oriented by modern MWD systems which are capableof reporting accurately the current bit and toolface hole angle andazimuth (i.e. the orientation with respect to the upper portion of thehole). It is accordingly possible to rotate the drill string until thetoolface has achieved the desired direction of deviation, and then tofix the drill string in place and commence the deviation by starting themotor to extend the hole in the desired deviated direction.

[0012] There are, however, a number of inherent problems in the use ofdirectional drilling, which affect the requirements of a drilling mud;namely:

[0013] As in deep water drilling, increased ranges of temperatures areencountered.

[0014] The annulus carrying the mud to the surface is no longer verticaland extends to far greater distances versus vertical wells.

[0015] Gravity on a horizontal hole pulls cuttings, weighting materialand particulate matter, not controlled by the drilling fluid, to thebottom side of the bore (not the bottom of the hole as in traditionaldrilling) and results in drag on the bore wall.

[0016] The amount of drilling mud required is increased since thedistances are greater, and the time required for the mud to reach theearth's surface also increases.

[0017] Curves and kinks in the hole's direction can accumulate cuttingsand additives.

[0018] In order to obviate or mitigate these problems, which can costoil and gas companies millions of dollars per hole, it is an object ofthe invention to provide drilling fluids with rheological propertiesparticularly appropriate for directional drilling including the improvedviscosity stability with temperature discussed above.

[0019] For background, it has been long known that organoclays (alsocalled organophilic clays) can be used to thicken drilling fluids. Seethe very early article by the employee of the assignee hereof J. W.Jordan, “Proceedings of the 10th National Conference on Clays and ClayMinerals” (1963), which discusses a wide range of drilling applicationsof organoclays from high polarity liquids to low polarity liquids.

[0020] Previously mentioned U.S. Pat. No. 6,462,096 discloses oil-basedinvert emulsion drilling fluids that provide more stable drilling fluidviscosity and anti-settling performance over varying temperatures whencompared to conventional fluids containing organoclays.

[0021] Patents of the prior art that show developments related to eitherdrilling fluids or chemistry of additives include the following:

[0022] U.S. Pat. No. 3,514,399 teaches the use of a mixed dimeracid-monocarboxylic acid salt of an imidazoline in a drilling fluid.

[0023] U.S. Pat. No. 5,260,268 describes a product introduced into awell borehole which encompasses water-based drilling fluids and shows acomposition comprised of a polycarboxylic acrylating agent reacted withan amine-terminated polyethylene of a molecular weight average from 600to 10,000. While ethoxylated amines are discussed as a surfactant whichmay be used in conjunction with the composition, there is no teaching ofapplications in an oil-based invert emulsion drilling fluid.

[0024] U.S. Patent Application Publication No. 2001/0009890 shows aninvert emulsion suitable for drilling a subterranean well which uses anester of a C₁ to C₁₂ alcohol and a C₈ to C₂₄ monocarboxylicacid—Ethomeen C/15 can be used as an agent in the invention described inthe application.

[0025] U.S. Pat. No. 5,536,871 issued to the assignee hereof describes arheological additive which comprises the reaction product of apolyalkoxylated nitrogen-containing compound such as polyoxyethylene (5)cocoalkylamine, a polycarboxylic acid including dimer acids and a liquiddiamine.

[0026] U.S. Pat. No. 5,610,110 also issued to assignee hereof shows animproved drilling fluid containing a reaction product of an alkoxylatedaliphatic amino compound and an organic polycarboxylic acid and a claybased organoclay.

[0027] U.S. Pat. No. 5,909,779 at Col. 4, lines 55 to Col. 5, line 15contains a large laundry list of surfactants, wetting agents andviscosifying agents conventionally used in oil-based drilling fluidsincluding fatty acids, polyamines, imidazoline derivatives andpolycarboxylic acids and soaps of fatty acids.

[0028] Recent Dow Chemical Company U.S. Pat. No. 6,291,406 describes awell treatment fluid using an amine surfactant to provide a sufficientlystable emulsion. Ethomeens are discussed, particularlybis(2-hydroxyethyl) cocamines and oleyamines.

[0029] Commercial rheological drilling fluid additives presentlyavailable on the market, however, tend to have increased viscosity whilethe fluid temperature is low, requiring increased pump pressure which inturn causes increased wear of the drilling gear. Increased pumpinghorsepower becomes necessary to pump drilling muds through longdistances, and increased down-hole pressure under pumping conditionsincreases fluid loss, fracturing and damage of the formation. Prior artmethods of reducing drilling fluid viscosity are not satisfactorybecause the resultant drilling fluids fail to maintain adequatesuspension characteristics when the fluid temperature changes, forexample, at down-hole conditions.

[0030] There is clearly an unfilled need which has been growing in thepast decade for drilling fluids that are able to maintain a relativelyconsistent rheological profile over a wide temperature range; it isbelieved that the below unexpected described invention fills this need.

SUMMARY OF THE INVENTION

[0031] The invention herein covers new additives that enable thepreparation of drilling fluids with viscosities that are less affectedby temperature over a temperature range from less than about 40° F. tomore than about 250° F. compared to conventional fluids. In addition,this invention permits the use of reduced amounts of organoclayrheological additives with the attendant reduction in cost. In fact, insome cases organoclays can be completely eliminated.

[0032] According to one aspect, this invention provides a mixturecomposition comprising as the first ingredient the reaction product of adi-, tri- or polyamine with an acid containing at least two carboxylfunctional groups to form a polyamide and as the second mixtureingredient an alkoxylated alkylamine. The alkoxylated amine can be addedto the polyamide before, during, or after its synthesis or addeddirectly to the drilling mud as a separate component.

[0033] According to another aspect, this invention provides a mixturecomposition comprising the reaction product of a di-, tri- or polyaminewith an acid containing at least two carboxyl functional groups to forma polyamide and as the second ingredient either (a) a fatty amide or (b)a mixture of a fatty amide and alkoxylated alkylamine which can be addedto the polyamide before, during or after its synthesis or added to thedrilling mud as a separate component.

[0034] In yet another aspect, this invention provides a reaction productcomprising a di-, tri- or polyamine, an acid containing at least twocarboxyl functional groups and an alkoxylated alkylamine.

[0035] In another aspect, this invention provides a reaction productcomprising a di-, tri-, or polyamine, an acid containing at least twocarboxyl functional groups, an alkoxylated alkylamine and a fatty amide.The fatty amide can be added prior, during or after the reaction oradded directly to the drilling mud as a separate component.

[0036] A further embodiment of the invention provides for a drillingfluid composition comprising an oil-based mud in which the aboveinventive reaction products are present individually or in combination.

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] FIG. 1 and FIG. 2 show that when an additive made according tothis invention is added to an oil-based drilling mud, the viscosity asexpressed by a Fann viscometer dial reading is much less temperaturedependent than when organoclays are used alone. It is also evident thatthe combination of 2 ppb of BENTONE® 155 with 0.5 ppb of the inventionhas a similar viscosity to 4 ppb of the organoclay at 180° F. and 2 ppbof the clay at 40° F. The value of this phenonenom will be obvious toone skilled in the art.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0038] The invention provides compositions that reduce the effects oftemperature on the viscosity of an invert emulsion drilling fluid. Theviscosity vs. temperature profile is maintained more uniformly from lessthan about 40° F. to greater than about 250° F. for extended periods oftime. When used in combination with organophilic clay, the inventionmaintains characteristics associated with organophilic clays in oil andsynthetic based drilling fluids.

[0039] Additionally, the additive has strong value in deep-waterdrilling. Among the main positive attributes are the reduced high andlow shear viscosity at sub-ambient temperatures as compared to adrilling mud exhibiting similar rheological properties at ambienttemperature with just organoclay alone as the rheological agent. Thisreduced viscosity at low temperature leads to a greater ability tocontrol formation pressure while minimizing the risk of lost returns.

[0040] The term “drilling fluid” conventionally denotes any of a numberof liquid and gaseous fluids and mixtures of fluids and solids (as solidsuspensions, mixtures and emulsions of liquids, gases and solids) usedin operations to drill boreholes into the earth. It is synonymous with“drilling mud” in general usage.

[0041] This invention particularly covers generally petroleum orsynthetic oil-based drilling fluids we call oil based drilling fluids.More particularly, it relates to an oil based drilling fluid oftenreferred to as an invert emulsion drilling fluid, which is a water inoil emulsion whose continuous phase is oil. The water phase, or internalphase, is typically a brine for example 25% calcium chloride. This wateror brine phase can range from 0% in all oil muds to in excess of 50% ininvert emulsion drilling fluids.

[0042] An important embodiment of this invention relates to a drillingfluid containing a composition which is a mixture or blend of (1) areaction product of a specific polyamine and a carboxylic acid with atleast two carboxylic moieties and (2) an alkoxylated amine. The use ofthis unique mixture as an additive for an invert emulsion drilling fluidsurprisingly improves the fluid's rheological properties. The resultantdrilling fluids have a relatively constant viscosity over a widetemperature range. More surprisingly, the viscosity of the drillingfluid of the invention is relatively low at reduced temperatures whileproviding sufficient viscosity under downhole temperatures to reducebarite sag and suspend drill cuttings.

[0043] The additive comprises the following. First discussed are thecomponents of the reaction product and its production.

[0044] Fatty Acids

[0045] Any carboxylic acid with at least two carboxylic moieties can beused for producing the reaction product component of the presentinvention. Dimer acids are preferred; dimer acids of C₁₆ and C₁₈ fattyacid are particularly preferred. Such dimer acids can be fullyhydrogenated, partially hydrogenated, or not hydrogenated at all. Usefuldimer acids also include products resulting from the dimerization of C₁₆to C₁₈ unsaturated fatty acids.

[0046] Generally when used, the dimer acids preferably have an averagefrom about 18, preferably from about 28 to about 48 and more preferablyto about 40 carbon atoms. Most preferably dimer acids have 36 carbonatoms.

[0047] Useful dimer acids are preferably prepared from C₁₈ fatty acids,such as oleic acids. Useful dimer acids are described in U.S. Pat. Nos.2,482,760, 2,482,761, 2,731,481, 2,793,219, 2,964,545, 2,978,4681,3,157,681, and 3,256,304, the entire disclosures of which areincorporated herein by reference.

[0048] Examples of most preferred dimer acids include the Empol® productline available from Cognis, Inc., Pripol™ dimer acids available fromUniqema and HYSTRENE® dimer acids formerly available from HumkoChemical.

[0049] It is recognized that commercially available dimer fatty acidscontain a mixture of monomer, dimer, and trimer acids. Preferably, inorder to achieve optimal results, the dimer fatty acid used has aspecific dimer acid content as increased monomer and trimerconcentration hinder the additive's performance. A person of ordinaryskills in the art recognizes that commercial products may be distilledor otherwise processed to ensure certain dimer content. Preferably,suitable dimer acid has a dimer content of at least 80%, more preferablyabove 90%.

[0050] Empol® 1061 with a dimer acid content of 92-96% is the preferreddimer acid for the present invention.

[0051] Polyamines

[0052] Polyamines having an amine functionality of two or more are usedfor the preparation of the reaction product of the present invention.Most preferably, polyamines from the family of polyethylene polyamineshaving a amine functionality of two or more should be used.

[0053] Di-, tri-, and polyamines and their combinations are mostsuitable for use in this invention. Representative such amines includeethylenediamine, diethylenetriamine, triethylenetetramine,tetraethylenepentamine and other members of this series. Branchedpolyamines and polyamines made with different alkyl groups can be used.

[0054] Triamines are most preferable, particularly diethylenetramine(DETA). DETA has been assigned a CAS No. of 111-40-0. It is commerciallyavailable from Huntsman International.

[0055] Making the Reaction Product

[0056] Specifics on processing of polyamines and carboxylic acids arewell known and can be used in making the reaction product of thisinvention. Preferably, the molar ratio between the amine functionalgroup and carboxyl functional group is between 4:1 and 1:1. Thepreferred range is from 1:5:1.0 to 3:1, most preferably about 2:1. Forexample, mixtures of more than one dimer acid and/or more than onepolyamine can be used. A representative manufacturing process isillustrated in the examples following hereafter. It should be noted thatthese reactions may generate imidazolines and other side products.

[0057] Alkoxylated Amines

[0058] Important to this invention in an important embodiment is that asuitable alkoxylated alkyl amine is mixed into or blended into thereaction product produced by the reaction of the carboxylic acid withthe polyamine as described above or is otherwise added directly to thedrilling mud.

[0059] Many alkyl alkoxylated amines are suitable for the presentinvention.

[0060] Any alkoxylated amine or similarly derivitized amines may beused. Suitable alkoxylated amines include amines of various degrees ofalkoxylation. Representative useful chemicals include the entireEthomeen®, Propomeen® and the Ethoduomeen® product lines of Akzo Nobel.

[0061] Preferred are amines with up to about 50 units of alkoxylationper molecule (e.g. Ethomeen® 18/60). More preferred are amines with upto about 15-25 units of alkoxylation (e.g. Ethomeen® C/25, T/25, S/25,18/25; Ethoduomeen® T/25). Most preferred are amines with up to about 10units of alkoxylation (e.g. Propomeen® C/12, O/12, T/12; Ethoduomeen®T/13, T/20; Ethomeen® C/12, C/15, C/20, O/12, O/15, T/12, T/15, S/12,S/15, S/20, 18/12, 18/15 and 18/20).

[0062] The most preferred amines are polyoxyethylene (5)cocoalkylamines, available, for example, under the tradename Ethomeen®C/15 from Akzo Nobel (New Brunswick, N.J.). Ethomeen® C/15 has a generalformula of RN[(CH₂CH₂O)_(m)[CH₂CH₂O)_(n)H] wherein R is cocoalkyl, andm+n=5.

[0063] Optionally, the alkoxylated amine may be added prior to thereaction between the dimer acid and polyamines, or blended after thereaction step. If added prior to the reaction or at the reactiontemperature, some esters may be formed between the dimer acid carboxylsand the alkoxylated amine hydroxyls.

[0064] In a preferred embodiment, the two components are mixed orblended in a weight ratio range of 95:5 to 5:95. The preferred ratiorange is 80:20 to 30:70 and the most preferred ratio is 55:45 reactionproduct to alkoxylated amine.

[0065] Fatty Amides

[0066] Optionally, additional ingredients such as fatty amides andrelated alkoxylated derivatives can be blended into or reacted with thepolyamide reaction product.

[0067] Suitable fatty amides, such as the Armid® product line by AkzoNobel includes high temperature melting amides of fatty acids that aresparingly soluble in drilling muds. Additionally, alkoxylated fattyamides, such as the Ethomid® product line by Akzo Nobel can be used.

[0068] While the above is the preferred formulation, other compositionsof varying molar ratios of raw materials can be used. Additionally,alternate commercial dimer fatty acids can be reacted with variousamines to generate the reaction polymer. It however should also be notedthat the alkoxylated amine could be reacted with the dimeracid/diethylenetriamine polymer generating compositions which can befurther modified by blending amine derivatives (e.g. fatty amides) andthis is intended to be included in this invention.

[0069] Preparation of the Drilling Fluids

[0070] The compositions of this invention described above will be usedprimarily as an additive to oil-based drilling fluids and mostparticularly for oil-based invert emulsion drilling fluids employed in avariety of drilling applications. The term oil-based drilling fluid isdefined as a drilling fluid in which the continuous phase is hydrocarbonbased. Oil-based fluids formulated with over 5% water or brine areclassified as oil-based invert emulsion drilling fluids. Commonly,oil-based invert emulsion drilling fluids will contain water or brine asthe discontinuous phase in any proportion up to about 50%.

[0071] A process for preparing invert emulsion drilling fluids (oilmuds) involves using a mixing device to incorporate the individualcomponents making up that fluid. Primary and secondary emulsifiers andwetting agents (surfactant mix) are added to the base oil (continuousphase) under moderate agitation. The water phase, typically a brine, isadded to the base oil/surfactant mix along with alkalinity controlagents and acid gas scavengers. Rheological additives as well as fluidloss control materials, weighting agents and corrosion inhibitionchemicals may also be included, and the agitation is continued to ensuredispersion of each ingredient and homogenize the resulting fluidizedmixture.

[0072] Suitable Oil Base

[0073] Diesel oil, mineral oil, synthetic oil, vegetable oil, fish oil,paraffinics, and/or ester-based oils can all be used as singlecomponents or as blends.

[0074] Suitable Brine Content

[0075] Water in the form of brine is often used in forming the internalphase of these type fluids. Water can be defined as an aqueous solutionwhich can contain from about 10 to 350,000 parts-per-million of metalsalts such as lithium, sodium, potassium, magnesium, cesium, or calciumsalts. The preferred brines used to form the internal phase of thepreferred fluid of the invention can also contain from about 5 to about35% by weight calcium chloride and may contain various amounts of otherdissolved salts such as sodium bicarbonate, sodium sulfate, sodiumacetate, sodium borate, potassium chloride, sodium chloride or formates(sodium, calcium, or cesium).

[0076] The ratio of water (brine) to oil in the emulsions of theinvention should generally provide as high a brine content as possiblewhile still maintaining a stable emulsion. Oil/brine ratios in the rangefrom about 97:3 to about 50:50 have been found to work satisfactorily,depending upon the particular oil and mud weight. Thus the water contentof a typical drilling fluid prepared according to the teachings of theinvention will have an aqueous (water) content of about 0 to 50 volumepercent.

[0077] Suitable Emulsifiers

[0078] In order to form a more stable emulsion, a emulsifier can also beadded to the external, the internal or both phases of the drillingfluid. The emulsifier is preferably selected from a number of organicacids which are familiar to those skilled in the drilling fluid area,including the monocarboxyl alkanoic, alkenoic, or alkynoic fatty acidscontaining from 3 to 20 carbon atoms, and mixtures thereof. Examples ofthis group of acids include stearic, oleic, caproic, capric and butyricacids. Adipic acid, a member of the aliphatic dicarboxylic acids canalso be used. More preferred surfactants or emulsifiers include fattyacid calcium salts and lecithin. Most preferred surfactants oremulsifiers include oxidized tall oil, polyaminated fatty acids, andpartial amides of fatty acids.

[0079] An important class of heterocyclic additives which we believeassist in regulating the flow properties of the drilling muds accordingto the invention are the imidazoline compounds. Other important membersof this heterocylic group are alkylpyridines.

[0080] Industrially obtainable amine compounds for use as emulsifiersare often derived from the epoxidation of olefinically unsaturatedhydrocarbon compounds with subsequent introduction of the N function byaddition to the epoxide group. The reaction of the epoxidizedintermediate components with primary or secondary amines to form thecorresponding alkanolamines is of significance in this regard.Polyamines, particularly lower polyamines of the correspondingalkylenediamine type, are also suitable for opening of the epoxide ring.

[0081] Another class of the oleophilic amine compounds useful asemulsifiers are aminoamides derived from preferably long-chaincarboxylic acids and polyfunctional, particularly lower, amines of theabove-mentioned type. The key factor in their case is that at least oneof the amino functions is not bound in amide form, but remains intact asa potentially salt-forming basic amino group. The basic amino groups,where they are formed as secondary or tertiary amino groups, may containhydroxyalkyl substituents and, in particular, lower hydroxyalkylsubstituents containing up to 5 and preferably up to 3 C atoms inaddition to the oleophilic part of the molecule.

[0082] Suitable N-basic starting components for the preparation of suchadducts containing long-chain oleophilic molecule constituents aremonoethanolamine or diethanolamine.

[0083] Weighting materials are also often used to weight the well borefluids of the invention to a density in the preferred range from about 8to 18 pounds per gallon and greater. Weighting materials well known inthe art include barite, ilmenite, calcium carbonate, iron oxide and leadsulfide. The preferred weighting material is commercially availablebarite.

[0084] Organophilic Clays. Organoclays made from bentonite, hectoriteand attapulgite clays can be added to the inventive drilling fluids.There are a large number of suppliers of such clays in addition toElementis Specialties' BENTONE® product line including RockwoodSpecialties, Inc. and Sud Chemie GmbH. Although organoclay can be auseful component, it is not a necessary component of the drilling fluid.

[0085] Blending Process

[0086] Drilling fluids preparations preferably contain between ¼ and 15pounds of the inventive mixture per barrel of fluids, more preferredconcentration is ¼ to 10 pounds-per-barrel and most preferably ¼ to 5pounds-per-barrel.

[0087] As shown above, a skilled artisan will readily recognize thatadditional additives: weighting agents, emulsifiers, wetting agents,viscosifiers, fluid loss control agents, and other agents can be usedwith this invention. A number of other additives besides rheologicaladditives regulating viscosity and anti-settling properties, providingother properties, can also be used in the fluid so as to obtain desiredapplication properties, such as, for example, anti-settling agents andfluid loss-prevention additives.

[0088] The drilling fluids of the present invention generally have alower viscosity at 40° F. than conventional muds formulated withsufficient organoclay to provide suspension at bottom hole temperatures.When used in drilling operations, the present drilling fluids allow theuse of a lower pumping power to pump drilling muds through longdistances, thereby reducing down-hole pressures. Consequently, fluidloss, fracturing and damage of the formation are all minimized. Drillingfluids of the present invention also advantageously maintain thesuspension characteristics typical of higher levels of organoclays athigher temperatures. The present invention is particularly useful indeep water drilling when the mud is cooled in the riser. A mud using thedescribed invention will maintain a reduced viscosity increase in theriser when compared to drilling fluids containing conventionalrheological additives.

EXAMPLES Example 1 Preparation of the Polyamide Reaction Product

[0089] Empol® 1061 (792.9 grams) was placed in a 2 liter, 4-neck,preweighed reactor equipped with a Barrett distilling receiver and aFriedrichs condenser. The Empol® 1061 was heated to 100° C. and thendiethylenetriamine (190.6 grams) was added. The contents were heated to240° C. under a nitrogen blanket while mixing at 300 RPM. A reactionoccured with the liberation of water, which was condensed in a receiver.The reaction was allowed to continue until the acid value was ≦2.0 (mgKOH/gram). The reaction was halted and the reactor reweighed. A samplewas taken, labeled Sample A, and given a lot number for further studies.

Example 2 Preparation of Inventive Mixture Using the Product of Example1

[0090] Sample A was allowed to cool to 80° C. under agitation. Ethomeen®C/15 (821.8 grams) was added slowly while mixing at 500 RPM. Thecomposition was mixed for 15 minutes. All of the Ethomeen® C/15 wasincorporated into the mixture. The resulting product was poured into anappropriate storage container.

Example 3 Preparation of Reaction Product 2

[0091] Empol® 1008 (635.2 grams) and Ethomeen® C/15 (692.1 gram) wereplaced in a 2 liter, 4-neck, preweighed reactor equipped with a Barrettdistilling receiver and Friedrichs condenser. The contents were heatedto 240° C. under a nitrogen blanket while mixing at 300 rpm. Thereaction was allowed to continue until the acid value was ≦5.0 (mgKOH/grams). Once the acid value was ≦5.0, diethylenetriamine (112.6grams) was charged to the reactor. The reaction continued for anothertwo hours at 240° C. After this time, Armid® HT (164.0 grams) was addedto the reactor and cooked for an additional 3 hours at 240° C. Theresulting product was poured into storage containers.

Example 4 Preparation of Drilling Fluid and Various Tests

[0092] A typical test mud was prepared comprised of a synthetic base oil(186 grams), primary emulsifier (4 grams), secondary emulsifier (2grams), 30% calcium chloride brine solution (75 grams) and lime (4grams). All components were mixed together for 15 minutes. The testadditive(s) was charged to the fluid and mixed for an additional 15minutes. Barite (215 grams) was next added and the fluid mixed foranother 15 minutes, total mixing time was 45 minutes. Properties of theresulting test mud were measured and evaluated.

[0093] After initial make up of all the drilling fluid (mud) andcharacterization was completed (120° F.), the drilling fluid (mud) wassubjected to a thermal treatment at 150° F. for 16 hours. Drilling fluid(mud) properties were measured at 40° F., 120° F., and 180° F. as perAPI RP 13-B standard practices.

[0094] A. Table 1 Summary TABLE 1 Drilling Fluid Formulation MudFormulation Lbs./BBL Synthetic Based Oil 186 Primary Emulsifier  4Secondary Emulsifier  2 30% Calcium Chloride Brine  75 Lime  4Rheological Additive See Tables for Concentrations Barite 215

[0095] A drilling mud formula for the purpose of evaluating aTheological additive performance.

[0096] B. Table 2 Summary

[0097] This below table represents a Bentone® 155 concentration study ina synthetic oil-based invert emulsion drilling fluid (mud). Table 2shows that an oil-based drilling mud incorporating organoclay alone as arheological modifier exhibits greater than 190% high shear rateviscosity increase at 4 ppb rheological agent when the temperature isreduced from 120° F. to 40° F. The drilling mud exhibits greater than a160% low shear rate viscosity increase at 4 ppb rheological agent whenthe temperature is reduced from 120° F. to 40° F. TABLE 2 BENTONE ® 155CONCENTRATION EVALUATION Rheological Additive BENTONE ® 155 AdditiveConcentration OFI 800 Viscosity 2 ppb 4 ppb ppb Test Temperature 40° F.120° F. 180° F. 40° F. 120° F. 180° F. 40° F. 120° F. 180° F. 600 RPMReading 113 48 36 169 58 37 215 87 62 300 RPM Reading 69 30 22 110 39 25158 59 42 200 RPM Reading 53 23 18 88 32 19 133 50 35 100 RPM Reading 3616 12 65 24 14 99 38 26  6 RPM Reading 13 6 3 26 10 6 48 20 14  3 RPMReading 13 5 2 25 9 6 45 18 13 Apparent Visc., cPs 57 24 18 85 29 19 10844 31 Plastic Visc., cPs 44 18 14 59 19 12 57 38 20 Yield Point, 25 12 851 20 13 101 31 22 Lbs./100 Ft²

[0098] C. Table 3 Summary: TABLE 3 Impact of Example 2 onViscosity:Temperature Profile Additive Concentration: BENTONE 155 (2.0ppb)/Example 2 (1.0 ppb) OFI 800 Viscosity Test Temperature 40° F. 120°F. 180° F. 600 RPM Viscosity 84 48 35 300 RPM Viscosity 50 31 24 200 RPMViscosity 40 25 20 100 RPM Viscosity 27 19 15  6 RPM Viscosity 12  9  6 3 RPM Viscosity 11  8  5 Apparent Visc., cPs 42 24 18 Plastic Visc.,cPs 34 17 11 Yield Point, Lbs./100 Ft² 16 14 13

[0099] Table 3 presents the effect of the product of Example 2 on theviscosity of an oil-based drilling mud. When 0.5 ppb of the additive iscombined with 2 ppb of BENTONE® 155, the 600 rpm Fann reading onlyincreases by 75% (48 to 84) when the temperature is reduced from 120° F.to 40° F. Two ppb of the BENTONE alone gave rise to a 135% increase(Table 2) under comparable conditions. The low shear rate viscosity,measured at 6 rpm, showed a 33.3% viscosity increase as the temperaturewas reduces whereas the BENTONE alone provided a 115% increase.

[0100] D. Table 4 Summary

[0101] Table 4 below presents the effects of the product of Example 3 onthe viscosity of an oil-based drilling mud. When 1 ppb of the additiveis used along with 3 ppb of BENTONE® 155, the 600 rpm Fann reading onlyincreases by 56.9% (65 to 102) when the temperature is reduced from 120°F. to 40° F. Four ppb of the BENTONE alone gave rise to a 190% increase.The low shear rate viscosity, measured at 6 rpm, showed a 29.4%viscosity decrease as the temperature was reduced. TABLE 4 Impact ofExample 3 on Viscosity:Temperature Profile Additive ConcentrationBENTONE 155 (3.0 ppb)/Example 3 (1.0 ppb) OFI 800 Viscosity TestTemperature 40° F. 120° F. 180° F. 600 RPM Reading 102  65 50 300 RPMReading 63 44 36 200 RPM Reading 48 36 30 100 RPM Reading 31 28 24  6RPM Reading 12 17 15  3 RPM Reading 11 16 14 Apparent Visc., cPs 51 3325 Plastic Visc., cPs 39 21 14 Yield Point, lbs./100 ft² 24 23 22

[0102] The foregoing description and examples have been set forth merelyto illustrate the invention and are not intended to be limiting. Sincemodifications of the disclosed embodiments incorporating the spirit andsubstance of the invention may occur to persons skilled in the art, theinvention should be construed broadly to include all variations fallingwithin the scope of the appended claims and equivalents thereof.

What is claimed is:
 1. A composition comprising: a) the reaction productof (i) a carboxylic acid with at least two carboxylic moieties and (ii)a polyamine having an amine functionality of two or more; and b) achemical selected from the group consisting of (i) alkoxylated alkylamines, (ii) fatty acid amides and (iii) mixtures thereof.
 2. Thecomposition of claim 1, wherein the carboxylic acid is a dimer fattyacid.
 3. The composition of claim 2, wherein the dimer fatty acid isselected from the group consisting of hydrogenated, partiallyhydrogenated and non-hydrogenated dimer acids with from about 20 toabout 48 carbon atoms.
 4. The composition of claim 1, wherein thepolyamine is a polyethylene polyamine.
 5. The composition of claim 4,wherein the polyamine is selected from the group consisting ofethylenediamine, diethylenetriamine, triethylenetetramine andtetraethylenepentamine.
 6. The composition of claim 4, wherein thepolyamine is diethylenetriamine.
 7. The composition of claim 1, whereinthe alkoxylated alkyl amine is an ethoxylated fatty amine.
 8. Thecomposition of claim 7, wherein the elkoxylated fatty amine is anethoxylated (5) cocoalkyl amine.
 9. The composition of claim 1, furthercomprising an organoclay.
 10. An oil based drilling fluid comprising thecomposition of claim
 1. 11. The drilling fluid of claim 10, furthercomprising an organoclay.
 12. The drilling fluid of claim 10, furthercomprising one or more emulsifiers.
 13. A composition comprising thereaction product of (a) a polyamine having an amine functionality of twoor more, (b) a carboxylic acid with at least two carboxylic moieties and(c) an alkoxylated alkyl amine.
 14. An oil based drilling fluidcomprising the reaction product of claim
 13. 15. A compositioncomprising the reaction product of a) a carboxylic acid with at leasttwo carboxylic moieties, b) a polyamine having an amine functionality oftwo or more, c) an alkoxylated alkyl amine and d) a fatty acid amide.16. An oil-based drilling fluid comprising the composition of claim 15.17. The drilling fluid of claim 16 further comprising an organoclay. 18.The drilling fluid of claim 15, further comprising one or moreemulsifiers.
 19. A composition comprising: a) the reaction product of(i) a carboxylic acid with at least two carboxylic moieties, (ii) apolyamine having an amine functionality of two or more and (iii) analkoxylated alkyl amine; and b) a fatty acid amide.
 20. An oil baseddrilling fluid comprising the composition of claim
 19. 21. The drillingfluid of claim 20 further comprising an organoclay.